This invention relates to the electrostatic measurement art, and more particularly to a new and improved inspection apparatus for determining the physical uniformity of a surface capable of being electrically charged.
One area of use of the present invention is in determining the surface quality and uniformity of photoconductive drums used in photocopiers, although the principles of the present invention can be variously applied to inspecting any drum surface capable of holding electrical charge. Heretofore, photoconductive drums have been inspected visually or by light scattering techniques to determine the presence of surface defects such as holes. These approaches, however, are indirect in that they provide no measure of charge properties of the drum surface and they provide information only about the reflective properties of the surface.
It would, therefore, be highly desirable to provide an apparatus for quickly and reliably determining the physical quality and uniformity of a charged drum surface in a manner providing a measure of the charge properties of the surface. It would also be highly desirable to provide in such apparatus the capabilities of accommodating variations in drum surfaces, effectively holding the drums during inspection, and rapid automatic removal of a drum from the apparatus upon completion of inspection.